System and method for reading optical codes on bottom surface of items

ABSTRACT

An automated checkout system and method of operation for reading encoded data on a bottom surface of an item using a data reader. The automated checkout system includes a leading conveyor section and a trailing conveyor section separated by a gap therebetween, where the item is transported across the gap as it moves between the conveyors. A first and second reading device are each positioned beneath the conveyor sections, where each reading device has a field of view projecting through the gap. The first reading device is configured to acquire a first set of scan data and the second reading device is configured to acquire a second set of scan data different from the first. In some embodiments, the first set of scan data may include two-dimensional area views of the encoded data, and the second set of scan data may include linescans of the encoded data.

RELATED APPLICATION DATA

This application is a nonprovisional of and claims the benefit under 35U.S.C. §119(e) from U.S. Provisional Patent Application No. 61/643,820,filed May 7, 2012, the disclosure of which is incorporated by referenceherein in its entirety.

BACKGROUND

The field of this disclosure relates generally to systems and methodsfor item checkout, and more particularly, to checkout systems having adata reader capable of reading encoded data on a bottom surface of theitem as the item passes through a read region of the data reader.

Data reading devices are used to read optical codes, acquire data, andcapture a variety of images. Optical codes typically comprise a patternof dark elements and light spaces. There are various types of opticalcodes, including one-dimensional codes, such as a Universal Product Code(“UPC”) and EAN/JAN codes, and stacked and two-dimensional codes, suchas PDF417 and Maxicode codes.

Data reading devices are well known for reading UPC and other types ofoptical codes on packages, particularly in retail stores. Some datareaders are installed at checkout stands or are built into a horizontalcheckout counter so that a read region is projected through atransparent window to read the optical code on the package. In a fullyautomated system, a customer normally places items on a counter, a deck,or a conveyor and the items are conveyed by the conveyor or other meansthrough the read region. In a semi-automatic system, a checkout clerktakes each item and moves it through the read region where the datareader captures the optical code.

One common data reader in such systems is an imaging reader that employsan imaging device or sensor array, such as a CCD (charge coupled device)imager or CMOS (complementary metal oxide semiconductor) imager. Imagingreaders can be configured to read both 1-D and 2-D optical codes, aswell as other types of optical codes or symbols and images of otheritems. Though some imaging readers are capable of using ambient lightillumination, an imaging reader typically utilizes a light source toilluminate the item being read to provide the required signal responsein the imaging device. An imager-based reader utilizes a camera orimager to generate electronic image data, typically in digital form, ofan optical code. The image data is then processed to find and decode theoptical code.

In one arrangement, the imaging reader may include one or more camerasoperating in a linescan mode and configured to capture a series ofsingle line views or scan lines of the optical code as the code crossesa read region. Multiple single line views of linescan mode may becombined to produce a raster image of the code, which is thereafterprocessed to decode the optical code. In another arrangement, theimaging reader may include one or more cameras operating in an area modeto capture a set of area views of the optical code as the code crossesthe read region. The area views may thereafter be stitched together toproduce a two-dimensional image that includes a complete image of theoptical code. The image may thereafter be processed to decode theoptical code.

In some embodiments of a checkout system, the read region for theimaging readers may be defined by a gap that separates two conveyingelements (e.g., conveyor belts). In such embodiments, the imagingreaders may be positioned beneath the conveying elements and positionedso that the field of view projects through the gap and allows theimaging readers to capture the optical code from the item as the itemcrosses the gap.

The present inventors have recognized certain limitations with presentcheckout systems. Certain checkout systems either cannot read or mayhave difficultly accurately capturing optical codes located on aconveyor-contacting, bottom surface of the item because the optical codeis blocked from view. Consequently, a checkout clerk or customer has toremove the item from the conveyor and reposition it so that the opticalcode is not on the bottom surface. In some cases, manual processing ofitems may be necessary, which leads to inefficiencies such as increasesin item processing time.

The present inventors have also recognized certain disadvantagesassociated with tunnel scanners that use imagers operating exclusivelyin either linescan mode or area mode to capture optical data on thebottom surface of the item. For instance, imagers operating in linescanmode require the item to move substantially uniformly across the readregion to acquire a decodable image. Erratic motion or wobbling of theitem as it crosses the read region may result in the data readeracquiring a distorted image of the optical code, which may preventaccurate decoding of the optical code. This issue with motion of theitem is exacerbated in tunnel scanning systems where the read region isdefined by a small gap separating two conveying elements, since itemstend to wobble as they traverse the gap.

On the other hand, while imagers operating in an area mode usually havefew issues handling erratic motion of items, such imagers have otherdisadvantages. For instance, area views typically require a large readregion to ensure that a sufficiently large portion of the optical codeis captured. However, in systems where the read region is defined by thewidth of the gap between conveying elements, it may be difficult toaccommodate the larger read region while avoiding undesirableconsequences. For instance, widening the gap to create a larger readregion may lead to issues with items becoming lodged in or fallingthrough the gap, or allowing dirt, dust, or other debris to interferewith the data readers.

The present inventors have, therefore, determined that it would bedesirable to provide an improved imager-based reader and an improvedtunnel or portal scanner system for automated checkout. Additionalaspects and advantages will be apparent from the following detaileddescription of preferred embodiments, which proceeds with reference tothe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an automated checkout system, accordingto a first embodiment, with leading and trailing conveyor sections andan exemplary six-sided, box-shaped item located on the leading conveyorsection and being moved toward a tunnel or portal scanner data capturedevice.

FIG. 2 is a simplified illustration of the automated checkout system ofFIG. 1 showing a data reader positioned beneath the conveyors on aninterior portion of a housing structure for the automated checkoutsystem, with the upper portion of the tunnel scanner removed.

FIG. 3 is a simplified illustration of the automated checkout system ofFIG. 1 illustrating the data reader having a dual camera system andmultiple illumination sources.

FIG. 4 is a simplified illustration of a side view of an alternativeembodiment of an automated checkout system with the tunnel scannerpositioned upstream of the gap, the system capturing a first view fromone camera implemented as a linescan view and a second view from anothercamera implemented as an area view.

FIG. 5 is a schematic diagram illustrating a concept for stitching aplurality of frames of image data to reconstruct the image.

FIG. 6 is a simplified illustration of an alternative embodiment for anautomated checkout system with the leading and trailing conveyorsvertically offset from one another.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

With reference to the drawings, this section describes particularembodiments and their detailed construction and operation. Theembodiments described herein are set forth by way of illustration onlyand not limitation. The described features, structures, characteristics,and methods of operation may be combined in any suitable manner in oneor more embodiments. In view of the disclosure herein, those skilled inthe art will recognize that the various embodiments can be practicedwithout one or more of the specific details or with other methods,components, materials, or the like. In other instances, well-knownstructures, materials, or methods of operation are not shown or notdescribed in detail to avoid obscuring more pertinent aspects of theembodiments.

In the following description of the figures and any example embodiments,it should be understood that an automated checkout system in a retailestablishment is merely one use for such a system and should not beconsidered as limiting. Other uses for an automated checkout system withthe characteristics and features described herein may be possible, forexample, in an industrial location such as a parcel distribution (e.g.,postal) station.

FIGS. 1-3 collectively illustrate a first embodiment of an automatedcheckout system 10. In one example operation, automated checkout system10 may be used to read and process an optical code on a bottom surface32 of an item 20 during a checkout process, such as in a retailestablishment or supermarket. In an example operation, a customer 36 orclerk 38 (hereinafter, collectively referred to as a “user”) places item20 onto a leading conveyor section 14 that transports item 20 in asubstantially linear direction of motion 34 toward a trailing conveyorsection 16. For convenience, leading and trailing conveyor sections 14,16 may collectively be referred to as conveyor 17 in the followingdescription.

Leading conveyor section 14 is spaced apart from trailing conveyorsection 16 by an elongated gap 18 that is oriented generally transverseto the substantially linear direction of motion 34. A bottom data reader40 is positioned below conveyor 17 and oriented to project a field ofview upwardly through gap 18. Data reader 40 is operable to capture theentire barcode label as the item 20 completes its transition across gap18. Item 20 is then transported on trailing conveyor section 16 to abagging area 46 where the user or other person can bag item 20. Furtherdetails of an example tunnel scanner, including a bottom data reader,are disclosed in U.S. application Ser. No. 13/356,417, filed Jan. 23,2012 (and published as U.S. Pub. No. 2012/0187195), and U.S. applicationSer. No. 13/357,356, filed Jan. 24, 2012 (and published as U.S. Pub. No.2013/0020392), the disclosures of which are herein incorporated byreference.

With reference to FIGS. 1-3, automated checkout system 10 includes ahousing structure 12 suitable for containing various components (asdescribed below) of automated checkout system 10. Automated checkoutsystem 10 may include a data capture device 11 having a first archsection 13 a and a second arch section 13 b coupled to housing structure12. First and second arch sections 13 a, 13 b may include one or moredata readers positioned therein for capturing various top and side viewsand reading barcode labels on item 20. Preferably, first arch section 13a is slanted forwardly in the direction of leading conveyor section 14and second arch section 13 b is slanted rearwardly in the direction oftrailing conveyor section 16 such that first and second arch sections 13a, 13 b form a generally V-shaped structure (e.g., as shown in FIG. 1).

As mentioned previously, leading conveyor section 14 is separated fromtrailing conveyor section 16 by gap 18 of a suitable size, such asapproximately twenty-five millimeters or less. Gap 18 extends along alength corresponding to the width of conveyors 14, 16. In someembodiments, gap 18 may be positioned between first arch 13 a and secondarch 13 b, such as in a substantially central location of data capturedevice 11 as shown in FIG. 1. In other embodiments, gap 18 may bepositioned upstream in relation to first arch 13 a (i.e., a positionwhere item 20 first crosses gap 18 and thereafter passes through arches13 a, 13 b of data capture device 11) or downstream in relation tosecond arch 13 b (i.e., a position where item 20 first passes througharches 13 a, 13 b of data capture device 11 and thereafter crosses gap18 as illustrated in FIG. 4). Further details and advantages of suchembodiments are disclosed in U.S. application Ser. No. 13/357,459, filedJan. 24, 2012 (and published as U.S. Pub. No. 2013/0020391, thedisclosure of which is herein incorporated by reference.

In some embodiments, the size of gap 18 may vary depending on manyfactors, such as, the intended use of automated checkout system 10. Forinstance, a retail establishment that processes items of various sizesmay want to keep gap 18 fairly small (e.g., on the order of less thanten millimeters) to accommodate the many thinner items, such as giftcards or greeting cards, and prevent those items from becoming lodged inor falling through gap 18. A warehouse, on the other hand, dealingprimarily with larger packages can have a larger gap 18 (e.g., on theorder of ten millimeters or more) without concern that the packages willfall through or become lodged.

In some embodiments, automated checkout system 10 may include a transferplate (not shown) positioned at least partially across gap 18 forhelping item 20 transition between sections of conveyor 17. Depending onthe size of gap 18 and the dimensions of item 20, transition betweensections of conveyor 17 may be difficult for some items, as they maybecome lodged in or perhaps fall through gap 18. The transfer plate maybe entirely comprised of a substantially transparent material, such asglass or other suitable material, through which data reader 40 can readthe optical code on item 20. Additional details and embodiments forautomated checkout systems using a transfer plate or other transitioningstructure are disclosed in U.S. patent application Ser. No. 13/356,417,previously incorporated by reference.

It should also be noted that although the embodiment in FIG. 1illustrates an open space between first and second arches 13 a, 13 b,arches 13 a, 13 b may be embodied in a single elongated tunnel formedover or around conveyor 17. Automated checkout system 10 may thus bepartially open and partially enclosed, such as the example illustratedin FIG. 1, or fully enclosed such as via a tunnel enclosure. Theconfiguration of first and second arches 13 a, 13 b creates an openarchitecture that provides some barrier/inhibition from a customerreaching into the read region, while also providing sight lines forallowing the customer to generally continuously observe items passingthrough arches 13 a, 13 b. A tunnel or portal scanner need not includeany fully enclosed tunnel structure or even semi-enclosed arches, but asuitable tunnel scanner may be constructed with more or less opennessbetween arches 13 a, 13 b.

In one embodiment, conveyor 17 is oriented and configured to transportitem 20, represented in FIG. 1 as a six-sided, box-shaped package havinga leading side 22, a trailing side 24, a checker side 26, a customerside 28, a top surface 30, and a bottom surface 32, through automatedcheckout system 10 in a substantially linear direction of motion 34. Thedescription regarding checker side 26 and customer side 28 is meant tofacilitate description and establish a frame of reference related to theposition of a customer 36 and a checkout clerk 38, as illustrated inFIG. 1. This description is not intended to be limiting. It should beunderstood that automated checkout system 10 may be used withoutcheckout clerk 38, and customer 36 (or clerk 38) may be positioned ateither side of automated checkout system 10. For convenience, item 20 isdescribed as a box-shaped package, but it should be understood that item20 may encompass other shapes, including irregularly shaped packages,such as a bag of oranges, potato chips, or the like. Additionally,although item 20 may contain an optical code on any one or more of thesix sides 22, 24, 26, 28, 30, and 32 described herein, for purposes ofdiscussion, the optical code will be described with reference to itsaffixation on bottom surface 32 (i.e., the conveyor-contacting surface).

In another embodiment, conveyor 17 may have a different directionalorientation, such as a semi-circular configuration wrapping aroundcustomer 36 or checkout clerk 38. In such a configuration, each sectionof conveyor sections 14, 16 may each have a curved portion and astraightened end. The straightened end of leading conveyor section 14may be substantially aligned with the straightened end of trailingconveyor section 16, and the respective straightened ends of theconveyors 14, 16 may be separated by gap 18. The operation regarding theprocessing and reading of item 20 may be substantially the same asdescribed with respect to an embodiment where conveyor 17 is disposedalong a substantially longitudinal axis.

With reference to FIGS. 2-5, automated checkout system 10 furtherincludes a bottom data reader 40 that may be positioned at least fiftymillimeters below conveyors 14, 16 and housed in housing structure 12.It should be understood that the following is a simplified descriptionof certain components of data reader 40 and may not include detailsrelating to a particular arrangement of optical elements, mirror sets,and other related features. In some embodiments, data reader 40 mayinclude an optical arrangement and other features similar to the datareader described in U.S. patent application Ser. No. 13/357,356, filedJan. 24, 2012, the disclosure of which is herein incorporated byreference. In another embodiment, components of data reader 40 may beconstructed and arranged in a pull-out drawer sub-housing within housingstructure 12, such as described in U.S. application Ser. No. 13/454,377,filed Apr. 24, 2012 (and published as U.S. Pub. No. 2012/0205448), thedisclosure of which is incorporated by reference herein.

Data reader 40 includes a first and second camera 42, 44 facing inopposite directions to acquire the optical code from item 20 as item 20crosses gap 18. First camera 42 may be oriented to capture thedownstream or trailing view (i.e., the view facing toward trailingconveyor section 16) and configured in an area mode to acquire one ormore two-dimensional area views 54 of the optical code as it is exposedwhen item 20 crosses the gap 18 (i.e., the read region). In an areamode, first camera 42 acquires an image of a portion or all of the readregion at a given time point, such as by using a global shutter imager.These area images may thereafter be stitched or pieced together (seeFIG. 5 and related discussion) to produce a complete image of bottomsurface 32 of item 20, which includes the optical code. Since the motionof item 20 is essentially frozen during the capture or acquisition of anarea image, a camera set on area view 54 to capture optical codes avoidsissues with wobbling or oddly-shaped items 20. Additional details andembodiments relating to cameras operating in area mode are disclosed inU.S. application Ser. No. 12/646,755, filed Dec. 23, 2009 (and publishedas U.S. Pub. No. 2010/0163627), the disclosure of which is hereinincorporated by reference.

Second camera 44 may be oriented to capture the upstream or leading view(i.e., the view facing toward leading conveyor section 14) andconfigured to capture images in linescan mode. In linescan mode, secondcamera 44 acquires one or more single line views 55 of at least aportion of the encoded data as item 20 passes through the gap 18. Thesesingle line views 55, in combination with the motion of item 20, maythereafter be processed, such as through an image stitching process, tocreate a composite image of the entire bottom surface 32 of item 20,including the optical code. One example method for capturing andprocessing scan lines is disclosed in U.S. application Ser. No.13/357,356, previously incorporated by reference. In other embodiments,the linescan mode may be replaced by a laser raster scanning method asdescribed in detail in U.S. application Ser. No. 11/279,365, filed Apr.11, 2006 (and published as U.S. Pub. No. 2006/0278708), and U.S. Pat.No. 6,142,376, issued Nov. 7, 2000, the disclosures of which are hereinincorporated by reference.

As briefly described above, first and second cameras 42, 44 arepositioned beneath conveyor 17. In one embodiment, first camera 42 ispositioned to acquire area views 54 of bottom surface 32 in thedownstream or trailing direction. Second camera 44 is positioned toacquire linescan view 55 in the upstream or leading direction. In suchconfiguration, the linescan view 55 is slanted or angled toward aconveyor end 50 of leading conveyor section 14. Similarly, the area view54 is slanted or angled toward a conveyor end 52 of trailing conveyorsection 16.

In other embodiments, the relative positions and orientations of firstand second cameras 42, 44 may be different. For instance, first camera42 may instead be oriented to acquire area views in the upstreamdirection and second camera 44 may instead be oriented to acquirelinescan views in the downstream direction. It should be understood thatreference to the positioning or use of two cameras (e.g., first andsecond cameras 42, 44) is for convenience only and not meant aslimiting. In other embodiments, data reader 40 may include any number ofcameras so that the data reader 40 can read the leading and trailingsides of the item 20. In addition, in other embodiments, cameras 42, 44may be arranged as side-by-side within data reader 40 instead of facingin opposite directions.

With reference to FIG. 4, first and second cameras 42 may be positionedto provide an angled view through gap 18. For instance, first camera 42may be positioned so that area view 54 reads through gap 18 at an angleα. Similarly, second camera 44 may be positioned so that linescan view55 reads through gap 18 at an angle β. In some embodiments, angles α, βmay each be approximately 30 degrees. In other embodiments, the anglesα, β may be different from one another. For instance, in an embodimentwhere conveyor sections 14, 16 are offset from one another (e.g., asshown in FIG. 6), angle α may be smaller than angle β to ensure thatboth first and second cameras 42, 44 can read through gap 18.

Preferably, conveyor 17 operates at a constant speed, e.g.,approximately 300 mm/s, to optimize the performance of data reader 40.To help monitor and regulate the conveyor speed, automated checkoutsystem 10 may include a conveyor motion sensor 15 (diagrammaticallyshown in FIG. 1 near leading conveyor section 14, but it may be placedin any suitable location). Additionally, it is preferred that items 20be placed on leading conveyor section 14 sequentially, in single file,to avoid data reader 40 mistakenly reading multiple items as a singleitem. In other embodiments, optimal performance of data reader 40 can beachieved with conveyor 17 operating at speeds higher or lower than 300mm/s without departing from the principles of the embodiments describedherein.

To aid in illuminating the optical code so that first and second cameras42, 44 acquire accurate images, data reader 40 may also include a firstillumination source 48 and a second illumination source 49. In someembodiments, first and second illumination sources 48, 49 comprise anarray of four LEDs generally arranged in a linear fashion and configuredto project illumination through gap 18 and onto leading side 22,trailing side 24, and bottom surface 32 of item 20 to illuminate theread region defined by the width and length of gap 18. The illuminationintensity of first illumination source 48 may be identical to theintensity of second illumination source 49 or it may differ depending onthe lighting needs of first and second cameras 42, 44.

Other numbers or arrangements of LEDs or other sources of illuminationmay also be suitable. For instance, in other embodiments, first andsecond illumination sources 48, 49 may not be housed within data reader40, but may instead be supported or located on a separate structure ofautomated checkout stand 10 and oriented to illuminate gap 18 asdescribed. In yet other embodiments, a controller may be incommunication with first and second illumination sources 48, 49 andconfigured for selectively controlling operation of first and secondillumination sources 48, 49. In still other embodiments, illuminationsources 48, 49 may provide pulsed or continuous illumination.

In one embodiment, first illumination source 48 is arranged in anangular configuration to project illumination through gap 18 in adirection generally coincident with the field of view of first camera42, that is, in a direction facing conveyor end 52 of trailing conveyorsection 16. Similarly, second illumination source 49 is arranged in anangular configuration to project illumination through gap 18 in adirection generally coincident with the field of view of second camera44, that is, in a direction facing conveyor end 50 of leading conveyorsection 14.

In this configuration, when item 20 is not blocking the illumination ofsecond illumination source 49 (i.e., when no item 20 is crossing gap18), the illumination is directed toward and blocked by a portion offirst and/or second arches 13 a, 13 b so that the illumination is out ofthe view of a human operator or a customer. Blocking some or all of theillumination from second illumination source 49 may be desirable becausethe illumination tends to be brighter than the correspondingillumination emitted from first illumination source 48. This disparityis due to the linescan operation of second camera 44 typically requiringhigher light intensity than the area mode operation of first camera 42.Therefore, the more intense light would be blocked by the arches 13 a,13 b and only the dimmer light from first illumination source 48 may bein view of a human operator or customer.

In some embodiments, data reader 40 may further include a processingunit 41 integrated therewith or as a separate unit in communication withdata reader 40. Processing unit 41 is preferably configured for decodingthe acquired optical codes from first and second cameras 42, 44 usingstandard image processing and stitching techniques. As a preliminarystep, processing unit 41 may also determine whether either or both ofcameras 42, 44 have captured a complete optical code. If neither cameras42, 44 have captured the optical code, processing unit 41 may send amessage to a display or other terminal alerting the user that the itemmay need reprocessing.

In instances where both cameras 42, 44 have captured the optical code,processing unit 41 may verify the accuracy of the system by comparingthe decoded optical code as acquired by first camera 42 with the decodedoptical code as acquired by second camera 44 to determine whether thedecoded optical codes match. In most instances, the decoded opticalcodes should match since both cameras 42, 44 are capable of individuallycapturing an optical code from the bottom surface 32 of the item 20.Accordingly, this comparison step may serve as a diagnostic measure todetermine whether automated checkout stand 10, or whether one or bothcameras 42, 44 are in proper working order.

However, in many cases, at least one of the cameras 42, 44 may not fullyor correctly acquire the optical code from item 20. For instance, whenitem 20 is wobbling or shaking, second camera 44 operating in linescanmode may acquire an incomplete or a partially illegible optical code.When processing unit 41 compares the results of the cameras 42, 44, thedecoded optical codes may not match. Accordingly, processing unit 41 mayinclude a routine or diagnostic tool for first determining whether thecameras 42, 44 captured a complete optical code prior to comparing thedecoded optical codes. This preliminary step would avoid processing unit41 from alerting the user that one or more components are malfunctioningsimply because the decoded optical codes did not match.

In an example operation, item 20 bearing an optical code on bottomsurface 32 is initially placed on leading conveyor section 14 andtransported in the direction of motion 34 toward gap 18. As item 20transitions from leading conveyor section 14 across gap 18, the secondillumination source 49 projects illumination onto bottom surface 32 toaid the second camera 44 in acquiring a number of linescan views 55 asitem 20 crosses gap 18. Each of these views may be stored in a memorymodule of data reader 40 or stored in a remote memory module forsubsequent processing and decoding. As item 20 continues across gap 18,first illumination source 48 projects illumination onto the bottomsurface 32 to aid first camera 42 in acquiring one or more area views 54of the same optical code. These images may be stored in the same or adifferent memory module as the linescan views 55 of second camera 44.Thus, for every item 20, both cameras 42, 44 will attempt to acquireimages of bottom surface 32 so that both area views 54 and linescanviews 55 are acquired. Thereafter, item 20 is transported on trailingconveyor section 16 to a bagging area 46 or another area.

Once the views 54, 55 have been acquired, processing unit 41 may firststitch all the frames together for each of the linescan views and areaviews corresponding to item 20. Since gap 18 is relatively narrow, boththe area views 54 and linescan views 55 will likely need to be stitchedor otherwise processed (see FIG. 5). Once the stitching process iscomplete, processing unit 41 may decode the optical codes.

FIG. 5 is a schematic diagram illustrating a concept for stitchingframes of image data. With reference to FIG. 5, one possible method forimage stitching and decoding linescan views or area views may includeoverlaying the frames with the code portions and comparing overlappingfeatures of the frames to recreate the entire optical code. Forinstance, the data reader (e.g., data reader 40) may capture a firstframe of the target data, such as frame i, at a frame rate ofapproximately 130 frames per second and determine whether frame iincludes a portion of the optical code containing a start sequence. Thestart sequence signals that the following frames will contain validoptical data and so the data reader will continue capturing the ensuingframes. Assuming frame i includes the start sequence, the subsequentframe captured, frame i+1, will typically contain a portion of an imagethat correlates or overlaps with a portion of the image in frame i andalso contain new data not included in the prior frame. The data readerwill continue gathering frames, such as frames i+2 and i+3, until itreads a valid stop sequence contained in one of the frames. Once thevalid stop sequence is captured, the data reader, or a separateprocessing system such as a computer, may then stitch together thecaptured views of the individual frames to recreate the optical code. Itshould be understood that the described method is simply one of a numberof methods that may be used to stitch frames together to recreate acomplete image.

After the images have been stitched together to reconstruct the entireoptical code, the processing unit decodes the optical code as acquiredby the data reader (i.e., by the individual imaging cameras). In caseswhere two or more cameras acquired an optical code, the processing unitmay compare the resulting codes and determine whether the decoded codesmatch. In instances where only one of the two cameras acquired acomplete optical code, the system may be programmed to instruct theprocessing unit to consider the complete optical code as the correctcode for the item 20.

In other embodiments, the image stitching process described above mayinstead be performed as a code stitching process where individuallydecoded fragments of the optical code are stitched together to form acomplete, decoded optical code. For example, as described previously,the process may begin by capturing individual frames and determiningwhether the captured frame includes an optical code containing a startsequence. Thereafter, each subsequent frame will be captured until avalid stop sequence is read. Throughout the process, each of thesecaptured frames (in either the area view or linescan view) shouldcontain a portion of the optical code, which may be processed anddecoded individually. Once all frames are analyzed in a similar fashion,each of the decoded code segments may be stitched together to recreate acomplete and decoded optical code.

In some instances, image stitching may not be required. For instance, ifthe optical code is small enough or gap 18 large enough, first camera 42may acquire an image of the entire optical code or enough of an opticalcode (such as a complete width of a one-dimensional optical code) in oneframe. Similarly, second camera 44 may acquire the entire optical codeor enough of the optical code (such as a single linescan traversing aone-dimensional optical code), in a single view or linescan. In suchinstances, processing unit 41 may skip the stitching process entirelyand proceed with the decoding process.

As briefly described previously, one potential issue with acquiringoptical codes using cameras implementing an area view is that the fieldof view is constricted by the relative narrowness (typically 25 mm orless) of gap 18. Because of this view constriction, a camera operatingin area view may have difficulty reading and piecing together largerfeature size barcodes. The area view 54 simply may not acquire largeenough pieces of the barcode to be properly pieced together and thendecoded. This difficulty is not so much of a problem for a cameraoperating in linescan mode because the linescan views generates a longraster view of arbitrary length that is able to encompass an arbitrarilylong optical code.

However, one of the difficulties of using a camera operating in linescanmode is that the item typically must move substantially uniformlythrough the field of view or the resulting image may be distorted. Inaddition, if the optical code is in the ladder orientation (i.e., wherethe bars in the barcode are perpendicular to the object motion), theimage distortion can prevent an accurate reading of the barcode. Thus,capturing images in linescan mode is a sensitive operation and typicallyrequires more uniformity and control of the object motion as compared toarea mode.

By using one camera implementing an area view and a second cameraimplementing a linescan view, automated checkout stand 10 is better ableto capture a larger variety of optical codes and thereby reduce errorrates associated with improperly captured or misread optical codes.Typically, both first and second cameras 42, 44 will accurately acquireand decode the optical codes. However, in instances where item 20includes a large feature size label, the linescan view will likely beable to more accurately acquire and decode the optical codes. On theother hand, the area view is better suited for acquiring and decodingthe optical codes on items 20 that are wobbling, shaking, or rolling asthey cross the gap 18.

FIG. 6 illustrates an alternative embodiment of an automated checkoutstand 10 where leading conveyor section 14 is raised in relation totrailing conveyor section 16 (i.e., the leading conveyor terminates at araised elevation proximate and relative to the trailing conveyor). Inthis configuration, when item 20 transitions between leading conveyorsection 14 to trailing conveyor section 16, item 20 crosses gap 18 andtilts or drops slightly onto trailing conveyor section 16. In suchembodiments, cameras 42, 44 may have a different angle of view than theembodiment described in FIG. 1 to ensure that the area view of firstcamera 42 and the linescan view of second camera 44 captures the opticalcode through gap 18.

Preferably, first camera 42 and second camera 44 are oriented such thatthe linescan view 55 of second camera 44 is maintained in the upstreamdirection and area view 54 of first camera 42 is maintained in thedownstream direction (see FIGS. 3 and 4). Such configuration would allowfor the intense illumination associated with linescan view 55 to face inthe direction of first and second arches 13 a, 13 b and out of view ofthe customer 36 or checkout clerk 38.

In some embodiments, automated checkout stand 10 may also include an airblower 58 positioned below conveyors 14, 16. Air blower 58 may directair flow across data reader 40 to keep lint, dust, dirt, and otherdebris from collecting thereon and thereby helping improve the accuracyand performance of data reader 40. Additional details and advantages ofsuch embodiments are disclosed in U.S. application Ser. No. 13/356,417,filed Jan. 23, 2012, previously incorporated by reference.

Automated checkout system 10 may further include sensor 60, such as anobject sensor or a temperature sensor, for activating air blower 58 whenitem 20 triggers sensor 60 as it moves toward gap 18. It should beunderstood that object sensor 60 may be placed at any suitable locationon automated checkout system 10. In some embodiments, sensor 60 oranother sensor may also trigger activation of the first and secondillumination sources 48, 49 to conserve energy use. For instance, whenthe sensor 60 is triggered, automated checkout stand 10 may determine anestimated time (based on the conveyor belt speed) for item 20 to arriveat gap 18, at which time the second illumination source 49 may beactivated, followed by the first illumination source 48. Once item 20has moved passed sensor 60, both illumination sources 48, 49 may bedeactivated until sensor 60 is triggered again.

Although the description above contains much specificity, these detailsshould not be construed as limiting the scope of the invention, but asmerely providing illustrations of some embodiments of the invention. Itshould be understood that subject matter disclosed in one portion hereincan be combined with the subject matter of one or more of other portionsherein as long as such combinations are not mutually exclusive orinoperable.

The terms and descriptions used herein are set forth by way ofillustration only and not meant as limitations. It will be obvious tothose having skill in the art that many changes may be made to thedetails of the above-described embodiments without departing from theunderlying principles of the inventions. The scope of the presentinvention should, therefore, be determined only by the following claims.

1. An automated checkout system for reading encoded data from a bottomsurface of an item, the automated checkout stand comprising: a housingstructure; a conveyor system comprising: (1) a leading conveyor sectionsupported on the housing structure and operable to receive and transportthe item bearing encoded data along a direction of motion, and (2) atrailing conveyor section supported on the housing structure andoperable to receive and transport the item along the direction ofmotion, wherein the trailing conveyor section is spaced apart from theleading conveyor section by a gap, the gap being elongated in onedirection and extending generally transverse to the direction of motion;a first reading device positioned beneath the conveyor system andconfigured for repeatedly reading through the gap, the first readingdevice having a first field of view oriented at a first angle relativeto the direction of motion, the first reading device configured toacquire a first set of scan data; and a second reading device positionedbeneath the conveyor system and configured for repeatedly readingthrough the gap, the second reading device having a second field of vieworiented at a second angle relative to the direction of motion, thesecond reading device configured to acquire a second set of scan datadifferent from the first set of scan data.
 2. The automated checkoutsystem of claim 1, wherein the first set of scan data comprises one ormore two-dimensional area views of at least a portion of the encodeddata as the item is transported across the first field of view.
 3. Theautomated checkout system of claim 2, wherein the second set of scandata comprises one or more scan lines of at least a portion of theencoded data as the item is transported across the second field of view.4. The automated checkout system of claim 1, further comprising: a firstillumination source configured to project a first illumination throughthe gap and onto the bottom surface of the item to illuminate the firstfield of view and aid the first reading device in acquiring the firstset of scan data; and a second illumination source configured to projecta second illumination through the gap and onto the bottom surface of theitem to illuminate the second field of view and aid the second readingdevice in acquiring the second set of scan data.
 5. The automatedcheckout system of claim 1, further comprising a portal scanner havingan arch section supported on the housing structure, the arch sectionpositioned upstream of the gap such that the item is transported throughthe arch section prior to being transported across the gap.
 6. Theautomated checkout system of claim 5, wherein the second illuminationsource is oriented to project the second illumination through the gapand onto a portion of the arch section such that the second illuminationis blocked by the arch section so as to not interfere with a humanoperator.
 7. The automated checkout system of claim 1, wherein thesecond reading device acquires a leading view of the item as the item istransported across the gap, and wherein the first reading deviceacquires a trailing view of the item as the item is transported onto thetrailing conveyor section.
 8. The automated checkout system of claim 1,further comprising a processor in communication with the first andsecond reading devices, the processor configured to process and decodethe first set of scan data to generate a first decoded optical code andthe second set of scan data to generate a second decoded optical code.9. The automated checkout system of claim 8, wherein the processorconfigured to process and decode the first and second set of scan datafurther includes the processor configured to stitch data of the firstset of scan data to generate the first decoded optical code and tostitch data of the second set of scan data to generate the seconddecoded optical code.
 10. The automated checkout system of claim 9,wherein the processor is further configured to: compare the firstdecoded optical code to the second decoded optical code; and determinewhether the first and second decoded optical codes match.
 11. A methodfor reading an optical code using a data reading system, the methodcomprising: receiving on a leading conveyor section an item bearingencoded data; transporting the item along a direction a motion on theleading conveyor section across a gap and onto a trailing conveyorsection, wherein the gap is elongated in one direction and extendsgenerally transverse to the item direction of motion; reading with afirst reading device through the gap along a first field of vieworiented at a first angle relative to the direction of motion;acquiring, in combination with movement of the item across the gap, afirst set of scan data with the first reading device; reading with asecond reading device through the gap along a second field of vieworiented at a second angle relative to the direction of motion; andacquiring, in combination with movement of the item across the gap, asecond set of scan data with the second reading device, wherein thefirst set of scan data is different than the second set of scan data.12. The method of claim 11, wherein the first set of scan data comprisesone or more two-dimensional area views of at least a portion of theencoded data as the item is transported across the first field of view.13. The method of claim 12, wherein the second set of scan datacomprises one or more scan lines of at least a portion of the encodeddata as the item is transported across the second field of view.
 14. Themethod of claim 11, further comprising: illuminating the first field ofview with illumination from a first illumination source to aid the firstreading device in acquiring the first set of scan data; and illuminatingthe second field of view with illumination from a second illuminationsource to aid the second reading device in acquiring the second set ofscan data.
 15. The method of claim 14, wherein the data reading systemcomprises a portal scanner having an arch section, the method furthercomprising: projecting the second illumination source through the gapand onto the arch section of the portal scanner such that illuminationfrom the second illumination source does not interfere with a humanoperator.
 16. The method of claim 11, further comprising: processing,via a processor in communication with the first and second readingdevices, the first and second sets of scan data; and generating a firstdecoded optical code from the first set of scan data and a seconddecoded optical code from the second set of scan data.
 17. The method ofclaim 16, further comprising comparing the first decoded optical code tothe second decoded optical code and determining whether the first andsecond optical codes match.
 18. The method of claim 17, furthercomprising stitching data of the first set of scan data to generate thefirst decoded optical code and stitching data of the second set of scandata to generate the second decoded optical code.